1. Field of the Invention
The present invention relates to filters for fluids. More particularly, the present invention relates to a filter system for fluids which utilizes filter media having a density different from the fluid (such as buoyant plastic beads when water is being filtered).
2. General Background of the Invention
In the filtration of fluids, filter media in the form of plastic beads or other particulates, such as diatomaceous earth or sand, is used to trap impurities. Typically, the filter media must be backwashed at predetermined intervals to keep the filter operating smoothly. This backwashing requires that the filter system be shut down, which can be quite inconvenient if continuous filtration is required during processing. If that is the case, then the process must be shut down while the filter is being backwashed, resulting in undesirable loss of production.
U.S. Pat. No. 5,126,042 discloses such a filter. In addition to the problem of needing to shut the system down to backwash the filter, static filters such as the one disclosed in the '042 patent can suffer from tunneling problems. Tunneling occurs when the filter media get clogged or bacterial gel builds up on the media, causing the filter media to stick together. Water breaks tunnels through the filter media and, following the path of least resistance, continues to travel through the tunnels instead of getting filtered by the filter media.